Three-dimensional integration of micro-optics in bulk silica glass by femtosecond laser direct writing: potential for industrial applications

摘要

Femtosecond laser direct writing technique is a powerful tool to integrate micro-optics, compared to a conventional method of assembling bulk micro-optics. This technique has a great advantage to save the assembly time and to confirm effects of integration in short time. In this paper, we demonstrate the integration of a micro grating and a diffractive lens inside bulk silica glass by using the femtosecond laser direct writing technique. The grating can split an input beam into several numbers of beams and the diffractive lens can focus the beam at its focal plane. Therefore the integrated optics has a new function of the combination of the splitting and the focusing. Moreover we demonstrate the integration of two diffractive lenses inside silica glass and a pin hole on its surface. The integrated optics can realize collimating and focusing simultaneously. From the industrial point of view, we propose two potential applications: a high efficiency photo detector and a miniature spectrometer. Device concepts and the evaluation results are described.